function f1() {}
const f2 = function () {};
const f3 = () => {};
const o = { f4() {}, f5: function () {}, f6: () => {} };
console.log(1, f1.prototype); // 1 {}
console.log(2, f2.prototype); // 2 {}
console.log(3, f3.prototype); // 3 undefined
console.log(4, o.f4.prototype); // 4 undefined
console.log(5, o.f5.prototype); // 5 {}
console.log(6, o.f6.prototype); // 6 undefined
